Method and apparatus for operating regenerators



Aug. 2, 1960 i c. J. scHlLLxNG METHOD AND APPARATUS PoR OPERATINGREGENERATORS Filed Feb. 3. 1956 2 Sheets-Shet 1 mkv INVETOR CLARENCE J.SGH/LING Aug. 2, 1960 c. J. scHlLLlNG METHOD AND APPARATUS FOR OPERATINGREGENERATORS Filed Feb. s, 195e 2 sheets-sheet?.-

- INVENTOR CLARENCE J. SGH/LING that the drawings are designed forpurposes of illustration only and not as a denition of the limits of theinvention, reference for the latter purpose being had to the appendedclaims. j V

In the drawings, in which similar reference characters denote similarelements throughout thev several views: Fig. 1 isa diagrammaticpresentation of a low temperature fractionating cycle embodying theprinciples of the present invention; Y

Fig. Z is an elevational view, partially in section, of a ow controldevice provided by the present invention, the control device being shownin open position and in operative relationship with a cold regenerator;

Fig. 3 is a view in vertical section of the control device of Fig. 2,the control device being shown in closed position; Fig. 4 is a view insection taken along the line 4-4 of Fig. 2, and

Fig. 5 is an elevational view, in section, of a ow control deviceconstructed in accordance with another embodiment of the presentinvention. The present invention provides a novel method of andapparatus for controlling the ow of relatively high pressure residualgas upwardly from regenerators in such a manner as to prevent theproduction of nes from the particles or pellets comprising the packingmaterial of the regenerators. According to the present invention thevelocity of the fluid stream owing upwardly through a regenerator ismaintained below a critical velocity, irrespective o'f the pressureinvolved, such that the resulting upward force on the packing materialis at all times less than the density of the packing material. Thus aquiescent bed of packingv material is obtained and the use of springloaded screens for preventing movement of the packing material isrendered unnecessary.

With reference more particularly to Fig. 1 of the drawings, there isdisclosed an air fractionating cycle which incorporates the principlesof the present invention. Al-

though the present invention is disclosed and described in theenvironment of separating air into low boiling point nitrogen and oxygencomponents, it is to be expressly understood that the principles of thepresent invention are applicable to the separation of other gaseousmixtures not limited to binary mixtures. As shown, the fractionatingcycle includes a two stage column 10 having -a high pressure section 11,a low pressure 12 and a conventional refluxing condenser 13. The cyclealso includes Atwo sets of cold regenerators 14 and 15, each comprisingone pair of cold regenerators 15, 16 and 17, 18, respectively. It is tobe expressly understood however, that additional sets may be providedand that each set may include more than two regenerators. A stream ofgaseous mixture under relatively high pressure, such as air at 80 poundsgage, for example, enters the cycle .through a conduit 20 seriallyconnected by a proportioning valve 21 to a conduit 22. Branch conduits23 and 24 are connected to the conduit 20 and to oppositely relatedindividual ports 25 and 26 of a pair of twopositioned switching valves27 and 28, respectively, the other individual ports 29 and 30 beingjoined by a conduit 31 communicating with the atmosphere through aconduit 32. The switching valves include common ports 33 and ,34connected to conduits 35 and 36 communicating with the upper ends of thecold regenerators 16 and 17, respectively. Conduits 37V and 38respectively extending `from the bottom ends of the regenerators 16 and-17 are connected to common ports of switching valves 39 and ,40. Onepair of oppositely disposed individual ports of fthe switching valves 39and 40 are connected to a common conduit 41 by way of conduits 42 and43, while Ythe other pair of individual ports are joined by acommonconduit 44. The upper endsrof vthe regeneratorslS and -,19 of the set 15are connected tothe conduit 22V and to a conduit 45 leading to theatmosphere'in a similar manner rbyfmeans of'switching valves 46 and 47,one pair of opposed individual ports being connected to the conduit 22by way of conduits 48 and 49 and the other pair of individual portsbeing joined together by a conduit 50 communicating with the conduit 45.The common ports of the switching valves 46 and 47 communicate throughconduits 51 and 52 to the upper ends of the regenerators 18 and 19,respectively. Also, the lower ends of the regenerators 18 and 19 areconnected through conduits 53 and 54 to the common ports of a pair ofswitching valves 55 and 56, the latter switching valves having one pairof opposed individual ports connected to the conduit 41 by way ofconduits 57 and 58, and another pair of individual ports connectedtogether by a common conduit 59.

With the switching valves in the positions shown in the drawing, a majorcomponent stream of the incoming air flows downwardly through theregenerator 16 while the remaining minor component stream ows downwardlythrough the regenerator 18, the proportions of the total air streamcomprising component streams being determined by the valve 21. Thecomponent air streams are cooled upon owing downwardly in theregenerators 16 and 18 which have been previously cooled in a mannerdescribed below, and leave the lower ends of the regenerators by way ofconduits 37 and 53 at a relatively low temperature, such asapproximately the dew point temperature corresponding to the existingpressure. The cold streams pass through conduits 42 and 57 and aremerged in the conduit 41, and the merged streams are conducted to anexpansion valve 61 and then introduced by way of a conduit 62 into thehigh pressure section 11 of the fractionating column 10. The highpressure section 11 includes a plurality of fractonating trays 63provided with liquid vapor contacting devices 64 of the bubble cap type,for example, and the gaseous mixture undergoes preliminary fractionationtherein producing liquid crude oxygen fraction collecting in a pool 65in the base of the high pressure section and gaseous nitrogen fractionwhich Hows upwardly into the reuxing condenser 13 where it is condensedby heat exchange with liquid oxygen product collecting in a pool 66 inthe base of the low pressure section 12. The liqueed high pressurenitrogen fraction ows downwardly from the refluxing condenser with aportion of the liquid providing reux for the high pressure section 11,and another portion collecting in a pool 67 formed by a trough 68. Astream of liquefied nitrogen fraction is withdrawn from the pool 67through a conduit 69, passed through an expansion Vvalve 70 andintroduced into the upper end of the low pressure section as reuxliquid. The feed for the low pressure section comprises a stream ofliquid crude oxygen fraction withdrawn from the pool 65 by way of aconduit 71, expanded in; an expansion valve 72 and introduced into lthelow pressure section at a mid point 73.

The low pressure section 12 includes a plurality of fractionating trays75 each provided with liquid vapor 'contact devices 76, and thefractionating process is completed therein producing a substantiallypure liquid oxygen product collecting in the pool 66, and a gaseousnitrogen product which flows upwardly in the dome of the low pressuresection and leaves the section through 'a conduit 77. The conduit 77 isjoined to the common conduit 44 connected between the switching valves'39 and 40. With the switching valves in the position shown, the streamof cold nitrogen` product gas passes through the 'cold regenerator 17and is exhausted from the cycle at substantially atmospheric temperatureand pressure lthrough the conduit 32. The oxygen product maybe withdrawnfrom the column 10 in liquid phase, or in gaseous phase through aconduit 78 communicating within the low pressure section above the poolYof liquid oxygen product 66. The conduitl 7'8 is joined to the commonconduit 59 connected to the switching valves 55 and 56, and with theswitchingyalves in.v the position shown in the drawing, the 'streamofgaseous oxygen 2gsm; rs1

product flows upwardly t-lrroughthe regen'erator 19 and leaves theAcycle through the conduit 45 aty substantially atmospheric temperatureand pressure. Y

The regenerators 116, 17, 18 and 19 are of similar conventionalconstruction,` and, although the regenerators of the sets 14 and 15 areof different capacity, it will only be necessary to describe in detailthe construction of one Iegenerator, 'such as the regenerator 16. Asshown in Fig. 2'the regenerator 16 comprises a hollow cylindrical casing80 closed at -its upper and lower ends by dished end plates 81 and 82,respectively, defining a chamber 83 substantially completely housing abed 84 of low temperature heat regenerator packing material in the formof a plurality of relatively small particles or pellets 85 of heatstoring material such as stone, quartz or metal. The lower end 82 of theregenerator is provided with a centrally disposed opening 86communicating with the conduit 3'7,pand a screen 87 is positioned withinthe chamber 83 overlying the opening `86 to prevent the pellets fromflowing out of the chamber 83 into the conduit 37. In this type ofregenerator the flow of cold product streams upwardly through thepacking material cools the particles of heat Vstoring material, and whenthe switching valves are operated to pass the incoming air streamdownwardly through the packing material the stored cold is transferredto and cools the air stream.

Asmentioned above, the incoming air stream in the conduit 20 is underrelatively high pressure, such as 8O pounds gage,A while the coldproduct nitrogen andoxygen streams enter the lower ends of theregenerators at a relatively. low pressure, 4 pounds gage for example.

Thus, when the switching valves are moved from one phase of operation tothe other, the regenerators previ- `ously passing a stream on incomingair will contain a residual volume ofrair under the relatively highpressure which must be exhausted from the upper ends of the regeneratorsbefore respective cold product streams may ilow therethrough. Accordingto the present invention the velocity of the residual air flowingoutwardly from the. top of the regenerators is controlled to allow theresidual air to exhaust as quickly as possible from the regeneratorswithout producing disturbing effects upon the. bed 84 of packingmaterial. This is accomplished by means of a novel liow control valve 90positioned at the upper ends of the regenerators in communicationbetween -the interior of the regenerators and their respective feedconduits 35, 36, 51 Iand 52. The ilow control valves 90 function tomaintain the rateof flow of fluid streams upwardly through theregenerators at all times slightly below a critical value above whichthe resulting upward force on the packing material 34 would exceed thedensity of the packing material, irrespective of the pressure drop ofthe residual air during the exhausting process. The flow control valvesalso function to Aallow normal rates of flow of the cold product streamsup- Vwardly through the regenerators and the streams of gaseous mixturedownwardly through the regenerators.

As shown moreparticularly in Figs. 2, 3 and 4 of the drawings, each offlow control valve 90 comprises a vertically disposed hollow cylindricalmember 91 having its lower end 92 extending through an opening in the`top end plate `81 of the regenerator in communication with theregenerator chamber 83 and secured thereto by any suitable means, suchas by welding, for example, and anupper end 93 provided with an annularflange 94 for forming a connection with one of the feed conduits 35, 36,51 or 52. The flow control valve further ind wardlyfrom Yits other end,the area of theopenings gradually decreasing in a `direction towardV theplate 99 and terminating in a plane spacedY upwardly from the lower endof the cylindrical member 100 to provide a continuous portion V102 atits lower end adjacent theplate 99. The piston 97' is mounted for axialmovement in a closed cylinder 103 rigidly supported in concentricrelation within the casing 91 by means of radial vanes 10d, the cylinderand the piston defining a` chamber 105. An annular ilange member'106 ispositioned within the casing below the cylinder 103, and is providedwith a centrally disposed opening 10.7 for receiving the hollowcylindrical member 100. The movable member is supported in Vitslowermost position in theV casing 91, as shown in Fig. 2, by means of aplurality of angularly spaced stop members 108'1ocated in a horizontalplane below the flange member 106 and projecting inwardly from thecasing to beyond the outer periphery of the plate member 99. The platemember 99 extends outwardly beyond the walls of the hollow cylindricalmember and presents an :annular flange 109 for contacting the lowerannular surface 110 of the flange member 106 to limit upward movement ofthe movable member 95 to the position shown in Fig. 3. The longitudinalspace between the planes of the annular flange member 106 and the stopmembers 108 and the length of the hollow cylindr-ical member 100 areproportioned to preferably maintain contiguous relationship between theouter surface of the hollow lcylindrical member and the opening 107throughout the range of longitudinal movement of the movable member 9S.Also, the strokeof the piston 97 in the cylinder 103 is Vat least equalto the range of longitudinal movement of the member-95 so that theopening 107 and the cylinder 103 function as guides for the .member 95.VA helical spring 111 is positioned in the chamber between the upper endsurface of the piston 97 and the end wall of the cylinder 103 tonormally urge the movable member 95 downwardly to the position showninFig. 2. A downward force is also applied to theV member 95 by thepressure of the Vfluid in the chamber 105 acting on the piston 97, thefluid being supplied to the chamber through a longitudinal passageway112 Yextending throughout the valve stem from the lower side hollowcylindrical member permits Ylimited uid ilow across the lilange member106 when 'the member 95 is in the latter position.

The effective area of the piston ,97 and the size of fthe spring 112 areproportioned with respect to the eifective area of the plate member 99so that the member 95 moves to its uppermost, or closed position, asshown in Fig. 3,` whenever the pressure of the fluid on the regeneratorside, or Vat the inlet of the casing 91 exceeds a predetermined value.In this position, the Huid flows from the inlet to the outlet onlythrough the orifices 113 and any desired predetermined maximum rate offlow.

may be established by calibration of these orifices.` YWhen the pressureof the fluid at the inlet drops .fro a value -such that the downwardforce presented by the spring 112 and the pressure ofthe liuid acting onthe piston 97 exceeds theupward force presented bythe pressure ofthefluid acting onI the plate member 9.9 the member 95 begins to movedownwardly from it/sposition shown in Fig.` 3.

` Upon suti'eient downward movement of the member `95,

thelower ends of the openings 101 extend downwardly beyond thelower'surfac'e of. the annular flange member 106 to allow uid How aroundthe periphery of the plate member 99 and through the opening 107. Due tothe tapered shape of the openings '1, the eiective sizeof the opening107 gradually increases as the member 9S moves further downwardly, andmaximum opening is attained when the member 95 moves to its lowermost oropen position, shown in Fig. 2. VIn the latter position minimumrestriction is olered to fluid ow through the casing 91 in eitherdirection.

The -ow control valves 90 are operable to automatically limit the rateof liuid flow therethrough to below a predetermined value whenever theregenerator inlet of the casing 91 is subject to a relatively highpressure, such as the relatively high pressure residual iluid existingin the regenerator chamber 83 upon the regenerator being switched whenpassing a stream of relatively high pressure gaseous mixture. 'Iheorifices 113 may be calibrated to maintain the rate of uid flow throughthe valve below a predetermined critical value for the maximum inletpressure as determined by the pressure of the fluid in the chamber 83.Also, the valve is operable to exhaust the relatively high pressureresidual fluid in the chamber 83 during the shortest period of timewhile maintaining the rate of fluid'ow through the casing 91 below thepredetermined critical value. This is accomplished by the feature ofincreasing the effective size of the opening 107 responsively todecreases in inlet pressure.

Operation of the ow control valves 90 will be more fully understood byconsideration of their performance in the fractionating cycle shown inFig. 1. Upon the switching devices 27, 28, 37, 38, 46, 47, 55 and 56being moved to the positions shown, streams of incoming gaseous mixtureunder relatively high pressure, such as compressed air, llow downwardlythrough the regenerators 16 and 18, while cold product streams underrelatively low pressure, such as nitrogen and oxygen product streams, owupwardly through the regenerators 17 and 19, respectively. During thisphase of operation the flow control valves 90 associated with eachregenerator are in their open positions, shown in Fig. 2, in which the-valves present a minimum restriction to uid ow therethrough in eitherdirection. The nitrogen and oxygen product streams are introduced intothe lower ends of the regenerators 17 and 19 at a pressure substantiallycorresponding to the pressure of the low pressure section of thefractionating column, which may be in the order of 4 pounds gage, forexample. Since the product streams are exhausted from the upper ends ofthe regenerators at atmospheric pressure, a pressure drop of 3 poundsper square inch will exist across the bed 84 of packing material. In aninstallation in which the regenerators are packed to a height of 2.1feet withheat adsorbing material having a density of 1-.10 pounds percubic foot, such as quartzite, a lifting force of approximately 20.6pounds per cubic foot will be exerted on the packing material by thepressure drop resulting from the ilow of the cold product streamsupwardly through the regenerators. This lifting force is about one fththe density of the packing material and is insuicient to disturb thebed.

When the switching valves are simultaneously moved to their other phasevof operation, the cold product streams are conducted upwardly throughthe regenerators 16 and 18, while the streams of gaseous mixture areconducted downwardly through the regenerators 17 andv 19 previouslycooled by the cold product streams. During this phase of operation theflow control valves associated with the regenerators 17 and 19 remain inthe fopen position, while the ow control valves connected to theregenerators 16 and 18 move to the closed posi-- tion, as shown in Fig.3, responsively to the residual volume of relatively vhigh pressure.gaseous mixture present in the latter regenerators at the time theswitching valves are operated. In the fractionation of air, as mentionedabove, the incoming airstream may be underar.

rposition shown in Fig. 3 and maintains the member 95 inclosed positionuntil the pressure of the air in the regenerator chamber 83 drops tobelow a critlcal value. When the tlow control valves associated with theregenerators 16 and 18 are closed, the residual air ows 'om therespective regenerators through the restricted orifices 1113. Theseorifices are calibrated to establish a maxi- 4mum permissible rate offlow, at the maximum pressure of the residual air, such that theresulting lifting force on the bed of packing material is less than thedensity of the packing material. In the case of quartzite packingmaterial of a density of 110 pounds per cubic foot packed to a height of2l feet inthe regenerators, the orifices -113 are calibrated to providea maximum permissible rate of ow, when subject to a pressure head ofpounds gage, to produce a pressure drop across the packing material lessthan the density of the packing material, or less than live times thepressure drop developed during upward flow of cold product streamsthrough the regenerators. Since the pressure drop varies as the squareof the mass liow and inversely as the density, the required orifice sizemay be easily calculated. In the present example, the orifices 113 aredesigned to provide a maximum permissible rate of flow less than 5.45times the rate of flow of the cold product streams.

As the residual air exhausts from the regenerator chamber, the pressureof the residual air remaining in the regenerator chamber decreasesv witha proportional decrease in the ow through the orifices 113. Inasmuch Vasit is advantageous to exhaust the residual air from the .regeneratorswithin the shortest period of time, the ow control valves arecharacterized in such a manner as to maintain, yupon a gradualdecreaseof the pressure of the Vresidual air in the regenerator chambers,l therate of flow Vthe open position responsively to a progressive pressuredrop in the regenerator chamber while maintaining the rate of flowbelowtheV maximum .permissible rate.

@When the member moves downwardly to a position Vwherein the closed endsofthe openings 111 extend Adownwardly beyond the lower surface of theannular flange memberA 106, the effective. size -of the orifice in theannular flange member 106 is increased and a predetermined rateOf-ow-may be maintained with a rer.duced pressure head.V The rate ofdownward movement of the member 95, and the shape of the openings 111,are proportioned in accordance with the pressure gradient within theregenerator chamber, to maintain the rate of flow from the regeneratorless than the maximum permissible rate of ow discussed above.

Y The liow control valves may be designed to operate Vresponsively toany degree of pressure drop to increase the effective size of theopening 107 presented by. the annular ilange member 106. The operatingrequirements ofthe cycle and thev sensitivity of the flow control valvesare primary factors in determining the degree of pressure reductionrequired for this operation. If desired, the variable orifice may becaused-to open responsively to a -pressure reduction of the order of onepound or less, ,however such an operation would require a ow controlvalve of extremely high sensitivity vand the resulting relativelyminutereduction of the exhaust periodmay not antritt- Y 9 ordinarily justifythe expense involved; In general,.a ilow controln valve operable toincrease` the size of'tlieoriiice responsively to a` regenerator chamberpressure intermediate the maximum residual air" pressure and the Vcoldproduct pressure,-or less,.may be manufactured at relatively low costtompossess the necessary sensitivity and also provide for the exhaust ofthe residual-airwithin a period of time which does not adversely Veiectcolumn operation. For example, ina fractionating cycle in which theV airstream is introducedat 80 pounds gage and the cold product streamsenterthe regenerators at `4 pounds gage, the elements ofthe flow controlvalves maybe proportioned to initiate downward movement of Ythe member95 upon the regenerator chamber pressure dropping to 40 pounds gage,andthereafter being operable to progressively `increase the sizeof theorice responsively to further `deduction of the pressure head to exhaustthe residual air and establish a-Yregenerator pressure of 4 pounds gagewithin a period-ofY lessfthanA five seconds. This short exhaustingperiod approaches the lower range of interrupted nitrogen ilow present`during operation of conventional fractionating cycles employingswitching tubular heat-exchangers or switching regenerators.Consequently,tthe provision of the iiow control-valves according to thepresent invention does not-increase the pressure in the low pressurelsectionlofV thel columnror reduce the l.rate'of evolution as comparedtoconventionalcyoles, but

inY some cases actually decreases the exhaust period and minimizes theireiect.

Another form of iiow control valve provided by the present invention isillustrated in Fig.- 5 of the drawings. As shown, the valve includes ahollow cylindrical casing 125 havingv its -lower end 126 secured to theupperl end plate S1 of a regenerator, such as the regenerator 16,-incommunication with the regenerator chamber; 83,` and its upperV endA 127provided withanannular flange 128. A hollow cylindrical member 2129,'VhavingV a closed upper end 13d,` is rigidly supported concentricallywithin the case 125 by means' of a pluralitypofradial vanes 131, and anelongated valve stem- 132 isv slidably mounted longitudinallyof thecasing in acentrally disposed opening 133formed in the end plate 130.VA- hollow valve member 131i including cylindrical sidewalls 135 andupper, and lower end plates 1361 and 137 respectively,

Yoverlies the lower end ofthe -valve stem 132, and `is rigidlysecuredthereto in concentric relation. The cylindrical sidewalls' 135are shaped so thatthe upper endof the valve member '13d-extends into thehollow cylindrical member 129 in sliding contact with its internalTsurface upon longitudinal movement of the valve stem 132.` The upper endof the valve member 134 and the cylindrical member 129 function asapiston and cylinder assembly and together deiine Va chamberV 138. Thelower end of the valve member 134 extends through a circular opening 139formed by an annular flange 140 secured tothe casingt1=25 4below thecylindrical member 129. The end plate 13,7 of the valve member 13'4extends outwardly beyond; the cylindrical side walls 135' and ispositioned below the annular ilanger140'to contact the lower surface ofthe latter Vflange and limit upward movement of the `valve stem 132. Thevalve stem 132 extends upwardly beyond the closed end 130of thecylindrical member 129 and is joined to Va valve operating member 141comprising a transversely disposed concentrically positioned cir-k jinside surface ofthe casing.V The plate includes a pluralunderstood thatvarious changes and substitutions may be 1 ity of downwardly dependingstop members 143 which function to limit downward movement of the valveoperative member and space the plate 1l41rfrom the upper 4surface of theclosed end 130 of the cylindrical member 129; Ihe valve 'stem 132 isprovided with a longitudinal passageway 144 extendingv from its lowerend 1'45 upwardly beyond the end plate 136 of the valve member where thepassagewayv communicates with" thek chamber t'through a portv 146. Thepassageway 144equalizes the pressures acting on the end-plates 136and'137,rand the end plates are proportioned to present equal eiectiveareas so that the valve member moves independently of the inletpressure. The end plate y137 is provided with a plurality of restrictedorices 147, and the side walls are provided with angular-ly spacedlongitudinally extending openings 148, of varyingA area, to control theow of fluid across the annular flange 140.

lnoperation of the flow control valve shown in Fig. 5, when thev inletis subject to. a relatively high pressure, such asfhigh pressureresidual air present inthe regen'- erator chamber 83 at the time theregenerator is switched to pass a stream of cold` product upwardlytherethrough, 'the high rate of iiow through the fixed annular orifice142 produces a pressure drop across the valve operating member 141causing the valve operating member and the valve member 134 to moveupwardly to its maximum or closed position shown in the drawing.position iiuid iiows only through the restricted orifices 147 and theseorifices may be calibrated to provide a predetermined maximumpermissible rate of `flow. As the inlet pressure decreases, the pressuredrop acrossv the valve operating member 141 decreases therewith, and acondition is eventually attained in which the upward force on the valveoperating member is less than the downward force determined by the massof the valve member 13d and its connected moving elements. When thelatter torce relationship exists, the valve member 134 moves downwardlyrelatively to the annular flange 14! to position the openings 14S belowthe lower surface of the annular ange and thus increase the size of theopening across the annular flange. Sincev the valve member movesindependently of the pressure of the iluid, the valve member isautomatically positioned relative to the annular ange to maintain aconstant rate of fluidow through the'casing 125 independently ofpressure variations. rthis form of flow control valve has particularutility in connection with regenerators, although it may be employed inother environments, since substantially the total volume of residual gasmay be exhausted from the regenerator chamber at a substantiallyconstant rate of flow no greater than the maximum rateof flowestablished by the fixed orifices 147.

There Vis thus provided by the present invention a novel cycle for theseparation of gaseous mixtures by liquefaction and fractionationincluding cold regenerators containing beds of packing material made upof small heat absorbing particles, in which the rate of ilow of highpressure residual gaseous mixture from the regeneratorstis controlled insuch a manner as to prevent disturbance of the bed and resultingproduction of fines due to attrition or crushing of the heat absorbingparticles, without increasing substantially the time required to exhaustthe residual gaseous mixture. The present invention also provides twoforms of liow Ycontrol valves which may be utilized with regenerator toachieve the foregoing operation. The flow control valves have utility inother environments requiringV a controlled rate of fluid flow, and oneof the how control valves is capable of maintaining substantiallyconstant rate of flow independently of pressure.

Although several embodiments of the invention have been disclosed anddescribed above, it is to be expressly made therein without departurefrom the spirit of the invention as well understood by those skilled inthe art.

Reference therefore will be had to the appended claims for a definitionof thelimits of the invention.

- What is claimed is: Y

` l. Method of operating a regenerator including a bed of-particles ofregenerative material and adapted to be switched between liirst andsecond operating phases, in which relatively high pressure iiuid flowsthrough the f11 regenerator during the-rst operating phase andrelatively low pressure tluid ilows through the regenerator duringthe'second operating phase, the method of controlling the flow ofrelatively high pressure fluid in the bed upon switching the regeneratorfrom one operating phase to the other operating phase which comprisesthe steps of restricting the flow of relatively high-pressure Iuid inthe bed upon the regenerator being switched from one operating phase tothe other operating phase to maintain the pressure drop across the bedless than a predetermined value to produce an upward force on the bedless than the density ofthe regenerative material, and establishingnormal unrestricted flow of uid in the bed upon the pressure of uid inthe bed decreasing to a predetermined low value, the predetermined lowvalue being such that normal unrestricted ow of fluid in the bed at apressure corresponding to the predetermined low kvalue establishes apressure drop across the bed which produces an upward force on the bedless than the density of the regenerative material.

2. Method of operating a regenerator including a bed of particles ofregenerative material and adapted to be switched between iirst andsecond operating phases, in which relatively high pressure uid flowsthrough the regenerator during the first operating phase and relativelylow pressure fluid ows through the regenerator during the secondoperating phase, the method of con` trolling the ow of relatively highpressure fluid in the bed upon switching the regenerator from oneoperating phase to the other operating phase which comprises the stepsof restricting the ow of relatively high pressure fluid in the bed uponthe regenerator being switched from one operating phase to the otheroperating phase to maintain the pressure drop across the bed less than apredetermined value to produce an upward force on the bed less than thedensity of the regenerative material,

decreasing the restriction to the flow of relatively high pressure fluidin the bed as the pressure drop across the bed decreases whilemaintaining the flow of fluid in the bed such that the resultingpressure drop across the bed is less than said predetermined value, andestablishing normal unrestricted flow of fluid in the bed upon thepressure of fluid in the bed decreasing to a predetermined low value,the predetermined low value being such that normal unrestricted flow offluid in the bed at a pressure corresponding to the predetermined lowvalue establishes a pressure drop across the bed Which produces anupward force on the bed less than the density of the regenerativematerial.

3. Method of operating a regenerator including a bed lof particles ofregenerative material and adapted to be switched between rst and secondoper-atingphases, in which relatively high pressure fluid ows downwardlythrough the regenerator during the iirst operating phase and relativelylow pressure luid ows upwardly through the regenerator during the secondoperating phase, the method of controlling the iiow `from theregenerator ot relatively high pressure fluid remaining in theregenerator upon the regenerator being switched from the rst operatingphase to the second operating phase to prevent movement of particlesforming the bed and the resulting production of fines, the methodcomprising the steps of restricting the flow of relatively high pressuretluid from the regenerator upon the the regenerator being switched fromthe tirst operating phase to the second operating phase to maintain thepressure drop across the bed less than a predetermined value to producean upward force on the bed less than the density of the regenerativematerial, and establishing normal unrestricted flow of uid from theregenerator .upon the pressure of fluid in the regenerator decreasingtoV a .predetermined low value, the, predetermined low value being'suchthat normal unrestricted ow of fluid in the bed at a pressurecorresponding to the predeterminedlow value establishes a pressure dropacross the bed which produces an up- 12 ward force on the bed less thanthe density of the regenerative material.

4. Method of operating a regenerator including a bed of particles ofregenerative material and adapted to be switched between tirst andsecond operating phases, in which relatively high pressure uid owsdownwardly through the regenerator during the lirst operating phase andrelatively low pressure diuid ows upwardly through the regeneratorduring the second operating phase, the method of controlling flow fromthe regenerator of relatively high pressure uid remaining in theregenerator upon the regenerator being switched from the first operatingphase to the second operating phase to prevent movement of particlesforming Ilthe bed and the resulting production of fines, the methodcomprising the steps Vof restricting the ow of relatively high pressureuid from the regenerator upon the regenerator being switched from thefirst operating phase to the second operating phase to maintain thepressure drop across the bed less than a predetermined value to producean upward force on the bed less than the density of the regenerativematerial, decreasing the restriction to the flow of relatively highpressure fluid from the regenerator as the pressure drop across the beddecreases while maintaining Vthe ow of fluid from .the regenerator suchthat the re- -tionating operation employing a switching regeneratorYincluding a bed of particles of regenerative material and adapted to beswitched betweenl first and second operjating phases, in whichrelatively high pressure gaseous mixture to be fractionated ows throughthe regenerator during the rst operating phase and relatively lowpressure cold product from the fractionating operation ows through theregenerator during the second operating phase, the method of controllingthe ow of relatively high pressure gaseous mixture in the bed uponswitching the regenerator lfrom one operating phase to the otheroperating phase to prevent movement of particles forming the bed and theresulting production of fines, the method comprising the steps ofrestricting the flow of relatively high pressure gaseous mixture in thebed upon the regenerator being switched yfrom one operating phase to theother operating phase to maintain the pressure drop across the lbed lessthan a predetermined value to produce an upward force on the .bed lessthan the density of the regenerative material, and establishing norm-alunrestricted iiow of gaseous mixture in the bed upon the pressure ofgaseous mixture in the bed decreasing to a predetermined low value, thepredetermined low value being such that normal unrestricted flow ofgaseous mixture in the bed at a pressure corresponding to thepredetermined lowv value establishes a pressure drop across the bedwhich produces an upward -force on 6. In the separation of gaseousmixtures by a frac- -including abcd of particles of regenerativematerial and adapted to be switched between iirst and second operatingphases, in which relatively high pressure gaseous mixture to befractionated Hows downwardly through the regenerator during the firstoperating phase and relatively low pressure cold product from theiractionating operation iiowsupward-ly through the regenerator duringthe second operating phase, the method of controlling the flowofrelativelyr high pressure gaseous mixture in the Y 13 bed ,uponvswitching the' regenerator from one operating phase to the otheroperating .phase to prevent movement of partieles forming the bed' andthe resulting production of lines, the method comprising the steps of.restricting the flow of relatively `high pressure gaseous ,mixturel inthe bed upon `the regenerator being switched`l from one operating phaseto the other operating phase to maintain the pressure drop across thebed less than a predetermined value to produce an upward force on thebed less than the density of the regenerative material, decreasing therestriction to the flow of relatively high pressure ygaseous mixture inthe' bed as .the pressure drop across the bed decreases whilemaintaining .the flow of gaseous mixture in the bed suc-h that theresulting pressure drop is less than saidy predetermined value, andestablishing norrnai unrestricted ilow of gaseous mixture in the bedupon the pressure of fluid in the bed decreasing to a predetermined lowvalue, Vthe predetermined low value being such that normal unrestrictedow of gaseous mixture in the bed at apressure corresponding to thepredetermined low value establishes a pressure drop across the bed whichproduces an upward force on the bed less than the density of theregenerative material.

Y 7. In the separation of gaseous mixtures by a` fractionatiiigoperation employing la switching regenerator including a bed ofparticles of regenerative material and adapted to be switched `betweenirst and secondoperating phases, iii which relatively high pressuregaseous mixture to be fractionated hows downwardly through theregenerator during the iirst operating phase and relatively low pressurecold product `from the fractionating operation flows upwardly throughthe regfnerator during the second operating phasefthe method ofVcontrollingfilow from the regenerator Vofgaseous mixture remaining` inthe regenerator upon the regenerator being switched Afrom the firstoperating phase to the second operating phase to prevent movement ofVparticles forming the bed and the resulting production of fines, themethod comprising the steps of restricting ow of Agaseous mixture fromthe regenerator upon the regenerator being switched from the iirstoperating phase tothe `second operating phase to maintain `theiiow fofnresidual gaseous mixture from the regenerator belowa maximum ilow suchthat the resulting pressure drop across` the bed of regenerative imaterial produces an upward force on the hed which is less than thedensity of the regenerative material, and establishing normalunrestrictedilow oi gaseous mixture in thekregenerator upon the gaseousmixture inthe regenerator dropping toa predeterminedl'ow pressure, Vthey' predetermined low value being such 'that norma-'1 unrestricted ow ofgaseous mixture from the'iregeneratorfat the predetermined low pressure(establishes ia pressure drop across the bed `of regenerativev material*producing an upward force on the bed less than the density of theregenerative material. I M

8. In the separation of gaseous mixtures byV a fractionating operationemploying a switching regenerator including a bed of particles ofregeneratiye material and adapted to be switched between Vfirstandse'cond operating phases, in which relativelyhigh pressure gaseousmixture to be fractionated yflows downwardly through the regeneratorduring the hrst operating phase audr'elatively low pressure cold productfrom the fractionating operation flows upwardly through theregeneratorduring the second operating phase, the method of' controlling t-he liowfrom the regenerator of gaseous mixture remaining in the regeneratorupon the regenerator being switched from the iirst operating phase totheA second operating phase to prevent movement of `particles formingthe bed and the resultingV production of fines, the method comprisingthe steps of restrictingthe Vflow of gaseous mixture from' theregenerator upon theV regenerator beingswitched from the first operatingphase to the vsecond operating phase to establish Va maximum flow of YV14. t x gaseous mixture from the regenerator` such that the re'-sultingfpres'sure'drop across the bedv of regenerative material producesan upward force on the bedV which is less than theV density of theregenerative material, decreasing the restriction to the flow of gaseousmixture frorn the -regenerator as the pressure of the gaseous mixturejinthe regenerator decreases while maintaining' the flow of gaseous mixturefrom the regenerator below the maximum ow, and establishing normalVunrestricted ilow of gaseous mixture from the regenerator upon thegaseous mixture in the regenerator dropping to a predetermined lowpressure, the predetermined low pressure being such that normalunrestrictedilow of gaseous-mixture'from the regenerator at thepredetermined low pressurev establishes a pressure drop across the bedofV regenerative material producing -anupward force on the bed less thanthe density of the regenerative material.

` 9. InV the separation'of gaseous mixtures by a fractionating-operationemployingv a switchingV regenerator including a bed of particles ofregenerative material and adapted to be switched between first andsecond operating phases, in which relatively high pressure gaseousmixture to be fractionated ows downwardly through the regenerator'during the first operating phase and relatively low pressure" coldproduct from the fractionating operation flows upwardly through theregenerator during the second operating phase, the method of controllingthe ilow from the regenerator of gaseous mixture remaining in theregenerator' upon the regenera'tor beingiswitched from' the Viirstloperating phase `1to the second operating phase to prevent movement ofparticles forming the bed and the resulting production of lines, themethod' cornprising the'rsteps of restricting the ow of gaseous mixturefrom the regeneiator upon the regenera'tor being switched :from thefirst operating phase to the second operating phase to establish amaximum ow of residual gaseous mixture from the regenerator such thatthe resulting pressure'drop across the bed of regenerative materialVproduces an upward force on the bed which is less than the densityofthe regenerative material, progressively decreasing' the restrictionto the flow of gaseous mixture frein the regenerator as the pressure ofthe gaseous mixture'in the regenerator decreases while at all timesmaintaining 'the now of gaseous mixture from the regenerator below 'themaximum flow, 4and establishing normall unrestrictedl flow of gaseousmixture from the regenerator upon the gaseous mixture in the regeneratordropping to a predetermined :low pressure, the predetermined lowpressure being such that normal unrestricted flow of gaseous mixturefrom the regenerator at the predetermined c low pressure establishes apressure drop across the bed of regenerfativernaterial producing `anupward force on the bed less than the density of the regenerativematerial.

l0. In ythe separation of gaseous mixtures by a fractionating operationemploying a switchingoregenerator :including '-a bed of particles ofregenerativey material and adapted to' beswitchedpbetween rst and secondoperating phases, in which relatively high pressure gaseous mixture' tobe` fractionated hows downwardly through the ViegelneratorAduring thefirst operating phase and relatively low pressugecoid product fromthefractionating operation `Vtllovvrs upwardly through the regeneratorduring the second operating phase', the method of controlling the owyfrom the regenerator of gaseous mixture remaining'in the re- Vgeneratorupon the regenerator being switched from the first operating phaseV tothe second operating phasefto o prevent movement of particles formingthebed andthe resulting production of lrines, the method comprising thesteps of restricting th'eiiowof` gaseous mixture from the regen'eratorupon the regenerator being switched from the Vvfirst peratinggphase to'theisecond operating phase to terial produces an upward force on thebed which is less than the density of the regenerative material,establishing normal unrestricted flow of gaseous mixture from theregenerator upon the gaseous mixture in the regenerator dropping to apredetermined low pressure, the predetermined low pressure of thegaseous mixture being such that normal unrestricted ow from theregenerator o f gaseous mixture at the predetermined low pressureestablishes a pressure drop across the bed of regenerative materialproducing an upward force on the bed less than the density of theregenerative material, and establishng normal unrestricted flow ofgaseous mixture downwardly through the regenerator upon the regeneratorbeing switched from the second operating phase to the first operatingphase.

`1l. In thel separation of gaseous mixtures by a fractionating operationYemploying switching regenerators each including a bed of particles ofregenerative material and adapted to be alternately switched betweenfirst and second operating phases, in which gaseous mixture Vunderrelatively high pressure flows downwardly through one of thevregenerators and relatively low pressure cold product from thefractionating operation ilows upwardly through another regeneratorduring the rst operating phase and in which gaseous mixture underrelatively high pressure Hows downwardly through the another regeneratorand relatively low pressure cold product flows upwardly through the oneregenerator during the second operating phase, the method of controllingthe ow from the regenerators of gaseous mixture under relatively highpressure remaining in the regenerators upon the regenerators beingswitched to ow relatively low pressure cold product upwardly through theregenerators to prevent movement of particles forming the beds andresulting production 'of' iines, the method comprising the steps ofestablishing normal flow of gaseous mixture downwardly through oneregenerator upon the one regenerator being switched from the secondoperating phase to the first operating phase, restricting the flow ofgaseous mixture from another regenerator upon the another regeneratorbeing switched from the rst operating phase to the second operatingphase to establish a predetermined maximum ilow of gaseous mixture fromthe another regenerator with a resulting pressure drop across the bed ofregenerative material producing an upward force on the bedless than thedensity ofv the regenerative material,

establishing normal unrestricted how of gaseous mixture ironr theanother regenerator uponthe gaseous mixture 1n the another regeneratordropping to a predetermined ,low pressure, the predetermined lowpressure of the gaseous mixture being such that normal unrestricted owofgaseous mixture from the another regenerator at the Ypredetermined lowpressure establishes a pressure drop across thebed of regenerativematerial producing an upward force on the bed less than the density ofthe regenerative material. Y

. l2.V In the separation of gaseous mixtures by fractionating operationemploying switching regenerators each including a bed of particles ofregenerative material and adapted to be alternately switched between rstand secfines, the method comprising the steps of establishing normal owof gaseous mixture downwardly through one regenerator upon the oneregenerator being switched from the second operating phase to the lirstoperating phase, restricting the ilow of gaseous mixture from anotherregenerator upon the another regenerator being switched from the firstoperating phase -to the second operating phase to establish apredetermined maximum ilow of gaseous mixture from the anotherregenerator such that the resulting pressure drop across the bed ofregenerative material produces an upward force on the bed ofregenerative material less than the density of the regenerative.material, maintaining normal flow of gaseous mixture downwardly throughthe one regenerator and progressively reducing the restricted ow ofgaseous mixture from the another regenerator as the pressure of thegaseous mixture in the another regenerator decreases while maintainingthe ow of gaseous mixture from the another regenerator below thepredetermined maximum flow until the pressure of gaseous mixture in theanother regenerator drops to a relatively low predetermined value suchthat the resulting pressure drop produced `across the bed uponunrestricted ow of gaseous mixture from the another regenerator at therelatively low value produces an Vupward force on the bed less than thedensity of the regenerative material, and providing unrestricted normalflow of gaseousV mixture from the another regenerator upon the pressureof the gaseous mixture in the another regenerator dropping to therelatively low value.

fll. In therseparation of gaseous mixtures by a fractionating operationemploying switching regenerators each including a bed of particles ofregenerative material and adapted to be alternately switched betweenfirst and second operating phases, in which gaseous mixture underrelatively high pressure flows downwardly through one of theregenerators and relatively low pressure cold product from thefractionating operation flows upwardly through another regeneratorduring the first operating phase and in which gaseous mixture underrelatively high pressure ows downwardly through the another regeneratorand relatively low pressure cold product ows upwardly through the oneregenerator during the second operating phase, the method of controllingthe ilow from the regenerators of gaseous mixture under relatively highpressure remaining in the regenerators upon the regenerators beingswitched to ow relatively low pressure cold product upwardly through theregenerators to prevent movement of particles forming the beds and the.resulting production of fines, the method comprising the steps ofestablishing normal flow of gaseous mixture `downwardly through oneregenerator upon the one regenond operating phases, in which gaseousmixture under relatively high pressure ows downwardly through one of theregenerators and relatively low pressure cold product from thefractionating operation iiows upwardly through another regeneratorduring the first operating phase and 1n which gaseous mixture underrelatively high pressure flows downwardly through Vthe anotherregenerator and relatively low pressure Vcold product ilows upwardlythrough the one regenerator during the second operating phase, themethod of controlling theow from the regenerators ofV gaseous mix-tureunder relatively high pressure remaining in the regenerators upon theregenerators being switched to flow relatively low pressure cold productupwardly through the regenerators to prevent movement of Werator beingswitched from the second operating phase to the rst operating phase,restricting the flow of gaseous mixture from another regeneratorV uponthe another regenerator being switched from the rst operating phase tothe second operating phase to establish a predetermined maximum ow ofgaseous mixture from the lanother re- `genator such thatthe resultingpressure drop across the bed of regenerativematerial produces an upwardforce on the bed less'than the Vdensity of theregenerative material,maintaining normal ow of gaseous mixture downwardly through the oneregenerator while progressively Q reducing the restriction to flow ofgaseous mixture from the another regenerator as the pressure of gaseousmixture in the another regenerator decreases to maintain ow of gaseousmixture from the another regenerator below the l predetermined maximumflow until the pressure of gaseous mixture in the another regeneratordrops to a predetermined low value such that the pressure drop producedyacross the bed upon unrestricted flow of gaseous mixture from theanother regenerator at the i relatively low value produces an upwardforce on the bed 17 l mixture in the another regenerator dropping to arelatively'lowv value, and establishing normal ow of gaseous mixturedownwardly through the another regenerator upon the another regeneratorrbeing switched from the, second operating phase to the iirst operatingphase, and establishing restricted flow of gaseous mixture from theoneregenerator upon the one regenerator lbeing switched from the firstoperating phase to the second operating phase, and controlling therestricted flow of gaseous mixture from 'the one regenerator to maintainthe flow of gaseous mixture from the one regenerator below thepredetermined maximum flow until the pressure of the gaseous mixtureintheV one regenerator drops to the relatively low'value and thereafterestablishing unrestricted normal How of gaseous mixture`from the oneregenerator.

14. 'In combination with a regenerator comprising a gnam bed ofVparticles of regenerative material and means inl cluding conduit meansand switching means for alternately flowing fluids under'diierentpressuresthrough the bed, valve means in 'the conduit means forcontrolling the ilow of iluid through the bed upon operation ofA theswitching-means toterminate the tlow through the regen- 'eratorofiuid'under one pressure/and' initiate the ilow through the regenerator ofHuid under ai differentY pressure, the: valvefmeans including meansoperable respon sively to apresslire 'diierential between fluid in theregenerator and fluid in the conduit means for restricting to apredetermined value the flow of uid iny the b'ed such that the pressuredrop developed across the. bed produces an upward force on the bedlessthan the density of the regenerativefmateri'al, and means forestablishingV normal unrestricted flow in the bed upon the pressuredifferential dropping to a value such that the resulting pressure dropproduces. upward force'on the bed less than the density of theVregenerativev material.

`15. In combination with a regenerator` comprising a bed ofparticles ofregenerative material and means including conduit-,means and switching'means forfflowing high pressure iluiddownwardly through the regeneratorwhenaswitched to oneoperating phase and for ilo'wing relatively lowpressure fluid upwardly through the regenerator when. switchedto anotheroperating phase, valve means in the' conduit meansfor controlling'theflow of highpressureluid in they regenerator uponV operation of theswitching means to terminate the ow through the regenerator of `highpressure fluid and initiateftheiiow through the,` regenerator ofrelatively low pressure fluid, the. valvenmeans. includingl meansoperable responsively tothe relatively high `pressure of the fluid inthe regeneratorfor `restricting to a predetermined value theA flow ofhigh pressure fluid from the regenerator such that the pressure dropdeveloped across the bed of regenerative material."` produces upwardforce on the bed less than the density oitheV yregenerative material,and means for establishing normal unrestricted flow from theregeneraltor upon-the'pressure of theuid in the regenerator dropping toavalue such that the resulting pressure drop across the bed produces anAupward force on the bed less than the density of the regenerativematerial.

1 6. "1n combination with aV regenerator comprising a bed of particleseti-'regenerative material and means including conduit means andswitching means for alternatelyfilowing fluids under diiferent pressurethroughfthe bed, valve means'iii the Aconduit means for controlling theflow of fluid in the bed upon operation of the switching means toterminate the flow through the regenerator of fluid under one pressureand initiate the flow through the regenerator of iiuid under a differentpressure, the valve means including means operable responsively to apressure differential between Huid in the regenerator and fluid in theconduit means for restricting to a predetermined value the flow of liuidin the bed such that the resulting pressure drop across the bed producesan upward force on the bed less than the density of the regenerativematerial, means for progressivelyA increasing l is .18. the ow of fluidin the bed as the pressure of the ud in the bed decreases, vand meansfor establishing. normal unrestricted ilow in the bed upon the pressuredifferential dropping to a value such that the resulting pressure dropacross the bed produces an upward force on the bed less than the densityof the regenerative material.

17. In combination with a regenerator comprising a bed of particles ofregenerative material and means including conduitrmeans and switchingmeans for flowing fluid under relatively high pressure downwardlythrough the bed when the switching means is moved to one phase and forilowing lluid under relativelyv low pressure Vupwardly through the bedwhen vthe switching means is moved to a second phase,.valve meansincluding means operable responsively to iluid under relatively highpressure in the regenerator upon the regenerator being switched to theiirst phase to restrict to a predetermined Value the flow of fluid fromthe bed ysuch that the pressure dropidevelopedacross the bed produces anupward force on the bed less than the density of the regenerativematerial, means for progressively increasing the ilow of fluid from theregenerator as the pressure of the fluidin the regenerator decreases,and means for establishing normal unrestricted ow from the regeneratorupon the pressure diierentiall dropping to a value such that thepressure drop developed across the bed produces 'an upward force on; thebed less than the .densitygof the regenerative material. c 18. In theseparation of gaseous mixtures by a fractionating operation employing aswitching regenerator including a bedof particles of regenerativematerial and adapted to be switched between first and second operatingphases, in which relatively high pressure gaseous mixture to befractionated flows downwardly through the regenerator during the iirstoperating stage and relatively low pressure product from thefractionating operation' flows upwardly through the regenerator duringthe second operating stage, valvularv means for controlling flow fromthe 'regenerator of gaseous mixture remaining in the regenerator uponthe regenerator being switched from the rs't operating phase to thesecond operating phase to prevent movement of particlesforming thel bedIand' the resulting production of'nes, the valvular means including meansfor restricting the flow of gaseous mixture from the regenerator uponthe regenerator being switched from the first operating phase to thesecond operating phase to maintain'the ow of gaseous mixture from theVregeneratory below a predetermined maximum fl'ow such that theresulting pressure drop across the bed ofregenerative material producesan upward force on they bed less than the density of the regenerativematerial, and means for establishing'normal unrestricted How of gaseousmixture from the: regenerator upon the gaseous mixture dropping toapredetermined low pressure, the .predetermined low pressure of thegaseous mixture being such that normal unrestricted: flow Yfrom theregenerator of gaseous mixture at the predetermined low pressureestablishes a pres'- sure drop across the bed of regenerative materialpro ducing an upward. force on the bed less than the density'oftheregenerative material. i i 1-9. In; the separation of gaseousmixtures by'afractionating'operatiort employing a switchingV regenerato'nf eind-ing; abed'o'parti'cles. of regenerative material" and' adaptedto be switched between rst and second operating phases, in whichrelatively high pressure gaseous mixture to be fractionated flowsdownwardly through the regenerator during the iirst operating phase andrelatively low pressure product from the fractionating operation flowsupwardly through the regenerator during the second operating phase,valvular means for controlling iow from the regenerator of gaseousmixture remaining in the'regenerator upon the regenerator being switchedfrom the iirst operating phase to the second operating phase to preventmovement `of particles forming the bed and the resulting production ofiines, said valvular means comprising means for restricting the flow ofgaseous mixture from the regenerator upon the regenerator being switched-from the rst operating phase to the second operating phase to establishla predetermined maximum flow of gaseous mixture at the relatively highpressure with the re- ,j

sulting pressure drop across the bed producing an upward force on thebed which is less than the density of the regenerative material, meansfor progressively decreasing the restriction to the ilow of gaseousmixture from the regenerator as the pressure of the gaseous mixture inthe regenerator decreases while maintaining the flow of gase- `ousmixture from the regenerator below the predetermined maximum flow, andmeans establishing normal unrestricted ow of gaseous mixture from theregenerator upon the gaseous mixture in the regenerator dropping to apredetermined low pressure, the predetermined low pressure being suchthat normal unrestricted ilow of gaseous mixture at the predeterminedlow pressure from the regenerator establishes a pressure drop across thebed of regenerative material which produces an upward force on glie bedless than the density of the regenerative mater 120. In the separationof gaseous mixtures by a fractionating operation employing switchingregenerators each including a bed of particles of regenerative materialand adapted to be alternately switched between rst and second operatingphases, in which gaseous mixture under relatively high pressure to befractionated llows downwardly through one of the regenerators andrelatively low pressure cold product from the fractionating operationows upwardly through another regenerator during the rst operating phaseand wherein relatively high pressure gaseous mixture ows downwardlythrough the another regenerator and relatively low pressure cold productows upwardly through the one regenerator during the second operatingphase, valvular means for controlling the flow from the regenerators ofgaseous mixture under relatively high pressure remaining in theregenerators upon the regenerators being switched to flow relatively lowpressure cold product upwardly through the regenerators to preventmovement of particles forming the bed and resulting production of iines,said valvular means comprising means for establishing normal flow ofgaseous mixture downwardly through one regenerator upon the oneregenerator being switched from the second operating phase to the lrstoperating phase, means for restricting the flow of gaseous mixture fromanother regenerator being switched from the flrst operating phase to thesecond operating phase, the restricted flow of gaseous mixtureestablishing a predetermined maximum ow of gaseous mixture from theanother regenerator such that the resulting pressure drop developedacross the bed of regenerative material produces a lifting force on thebed less than the density of the regenerative material, means formaintaining normal ow of gaseous mixture downwardly through the oneregenerator, means for progressively reducing the restriction to flow ofgaseous mixture from the another regenerator as the pressure of thegaseous mixture in the another regenerator decreases to maintain theflow of gaseous mixture from the another regenerator below thepredetermined maximum flow until the pressure of gaseous mixture in theanother regenerator drops to a relatively low value such that thepressure drop developed across the bed upon'unrestricted llow of gaseousmixture from the another regenerator at the relatively low valueproduces an upward force on the bed less than the density of theregenerative material, means providing unrestricted Ynormal flow ofgaseousmixture from the another regenerator when the pressure of thegaseous mixture drops to-the relatively low value, means establishingnormal low of gaseous mixture downwardly through the another regeneratorupon the another regenerator being switched from the second operatingphase to the rst operating phase, means for establishing a restrictedilow of gaseous mixture from the one regenerator upon the oneregenerator being switched from the rst operating phase to the secondoperating phase, and means for controlling the restricted flow ofgaseous mixture from the one regenerator to maintain the ow of gaseousmixture om the one regenerator below the predetermined maximum ow untilthe pressure of the gaseous mixture drops to the relatively low valueand thereafter establish unrestricted normal ow of residual gaseousmixture from the one regenerator.

21. In the separation of gaseous mixtures by a fractionating operationemploying a regenerator including a bed of particles of regenerativematerial and adapted to be switched between rst and second operatingphases, in which gaseous mixture under relatively high pressure ilowsdownwardly through the regenerator during the first operating phase andrelatively low pressure cold product from the fractionating operationflows upwardly through the regenerator during the second operatingphase, a fluid control valve connected to the regenerator and comprisinga casing having an inlet and an outlet, means for forming an opening ofvariable cross-section between the inlet and the outlet, the last-namedmeans including a valve member mounted Afor movement to a first positionin which a restricted opening is established between the inlet and theoutlet and a second position in which a relatively unrestricted openingis established between the inlet and the outlet and to positionsintermediate the rst and second positions, means operable toprogressively increase the size of the opening upon movement of thevalve member from the rst position to the second position, means fornormally urging the valve member tol the second position, means operableresponsively to a predetermined pressure of uid at the inlet for movingthe valve member to the first position, and means for moving the valvemember from the rst position in a direction towards the second positionin proportion to a drop in pressure of the fluid at the inlet below ithe predetermined pressure to establish a controlled flow through theopening.

References Cited in the file of this patent UNITED STATES PATENTS UNITEDSTATES PATENT OFFICE `CEBfrIFICArE 0F CORRECTION Patent Non, 2947y151 lAuguste, 1960 Clarence J Schilling It is hereb'l Certified 'that error'appears in the-printed Specification of the above -'numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Columnll, line 64, for "the the" read the column l2., line 34 for"tensty" read density g column lv lines 57 and 58.,- or "regenator" readregenerator Signed and sealed this 4th day of April 1961,

(SEAL) Attest: ERNEST W. kSWIDER XXQLXXXMXME ARTHUR w. CROCKER AttestingOfficer Acting Commissioner of Patents

